In the annals of strange religious groups, the Westboro Baptist Church of Topeka, Kansas, occupies a place of some distinction. Just 71 strong, its congregants made their name in the mid-90s by picketing gay pride rallies and the funerals of Aids sufferers, waving placards of unbelievable insensitivity ("Fags Eat Poop", "God Hates You"). More recently, they've ratcheted up their ministry of hate by taking the pickets to the funerals of soldiers killed in Iraq and Afghanistan ("Fag Military", "Thank God For Dead Soldiers").

Note these aren't gay dead soldiers (which, while no less hateful, would at least have a scintilla of logic). Any soldier's funeral will do. Their reasoning is that America is so depraved anyone who fights under her flag is a "fag enabler", and thus, an enemy of God.

The Phelps family consider these practises the true definition of Christian love, proving that what they lack in compassion they more than make up for in creative exegesis. For three weeks, I lived with the Phelps, attempting to get to know the people responsible for such a poisonous ministry. The pastor of the church, and the originator of the picketing concept, is Fred Phelps. He's also the patriarch of the family. But Gramps (as he's known in the family) is getting on in years, and these days it's his daughter Shirley who does most of the organising and the media appearances.

Shirley is in her 40s, a lawyer and mother of 11 children, and she has a kind of genius for religious invective. Several times I was on the receiving end of one of her biblical smackdowns, in which she heaped scriptural opprobrium on my head, then provided a graphic account of what it would be like for me to burn in hell for all eternity. It was a little like being waterboarded by John the Baptist.

Naturally part of my regimen was joining the Phelps on their pickets. These take place several times daily. As well as soldier's funerals, they also target local churches, civic buildings, visiting dignitaries, concerts by pop bands... In fact, there's almost nothing that the Phelps can't construe as part of the general climate of iniquity, and therefore a legitimate target. One weekly picket targets a hardware store that sells Swedish vacuum cleaners.

Apparently, Swedish authorities imprisoned a local pastor for preaching against homosexuality, thereby making the whole nation a target. For the newcomer, these pickets are bizarre not simply because of the outrageousness of the signs, but also because of how they clash with the banality of the family's interaction. For the Phelps, it's another day at the office - there's a watercooler ambience of relaxed chit-chat. Meanwhile, everyone - even the youngest children - carries placards saying "Thank God For 9/11" and "Your Pastor Is A Whore".

And yet, away from the pickets, they were - much of the time - very, very normal. Not just normal, but intelligent and urbane. They're not hillbillies, they're urban professionals - several work as lawyers in Topeka. The young members look like kids you'd run into at the mall. Weird Christian women are supposed to have sallow skin and dress in headdresses, but the Phelps girls were all-American, with long hair and good teeth. They listened to indie bands like the Killers and the Kooks and could banter humorously on non-biblical subjects. If anything, the hostility they've created seems to have forced them closer together, and, among themselves at least, they're a warm, loving family (which explains why the younger members don't all flee the minute they can afford a bus ticket).

As for Gramps, I had two interviews with the man. In my first encounter, I asked him how many children he had. For some reason he took exception to this, which set the tone for the second encounter. This took place in church one Sunday at the end of one of his sermons, preached on the subject of America's coming tribulations. "You're going to eat your babies!" he bellowed. Gramps still had the remnant of a folksy, plain-spoken charm, but the dominant note in his personality was a bitter contempt for humanity in general and me specifically. In an effort to keep the conversation going, I trotted out some bible quotes I'd memorised the night before. The interview was over in about five minutes. It seemed I was a hell-bound sinner. At least I was in good company.

Did I make any headway? A little, with the girls. In challenging circumstances, I console myself with the thought, expressed by Friedrich Nietzsche, that "Even when you lie, you nevertheless tell the truth with the shape your mouth makes when you are doing so." Being young and hopped up on hormones, the junior Phelps couldn't help telling a story with the shape of their mouths. One girl appeared to short-circuit when pressed on the subject of boyfriends, and later expressed angry bafflement that the Phelps' "caring" ministrations were so little appreciated by the locals. Even Shirley showed signs of empathy on the way to a soldier's funeral, though she quickly stifled them with a flight of bible talk.

I found a lot to like about the Phelps. They have a strong family unit, and Gramps aside, they were open and hospitable. It was fascinating to see the power of a family to create its own bizarre ideology and pass it down through the generations. But I guess I'll be seeing you all in hell.